Ultrastructural studies of epithelial, stromal, and endothelial cells of the cornea will be made during experimentally induced disciform keratitis following herpesvirus infection in animals. The immunocytochemical localization of HSV antigen, anti-HSV antibody, and antigen-antibody complexes will also be described at the ultrastructural level. Different strains of herpes simplex virus will be used for comparative studies. Corneal buttons and biopsy specimens obtained from human patients with disciform keratitis, and anterior chamber fluid will also be used. Transmission and scanning electron microscopy will be employed for the ultrastructural studies. This investigation should provide sufficient information concerning the pathogenesis of disciform keratitis at the cellular level to determine the most likely causes and permit separation of the clinical syndromes. This information is important and necessary in deciding on a rational program of treatment. The decision to use topical antivirals, systemic antivirals, or corticosteroids must be based on an understanding of the cellular events responsible for the clinical syndrome.